Numerous manufacturing processes require the use of ultrapure liquids, such as acids, solvents, bases, photoresists, slurries, cleaning formulations, dopants, inorganic, organic, metalorganic and biological solutions, pharmaceuticals, and radioactive chemicals. Such applications require that the number and size of particles in the ultrapure liquids be minimized. In particular, because ultrapure liquids are used in many aspects of the microelectronic manufacturing process, semiconductor manufacturers have established strict particle concentration specifications for process chemicals and chemical-handling equipment. Such specifications are needed because, should the liquids used during the manufacturing process contain high levels of particles or bubbles, the particles or bubbles may be deposited on solid surfaces of the silicon. This can, in turn, lead to product failure and reduced quality and reliability.
Accordingly, storage, transportation, and dispensing of such ultrapure liquids require containers capable of providing adequate protection for the retained liquids. Collapsible liner-based containers, such as the NOWPak® dispense system marketed by ATMI, Inc., are capable of reducing such air-liquid interfaces by pressurizing, with gas or fluid, onto the liner, as opposed to directly onto the liquid in the container, while dispensing. Specifically, such dispense systems may include an indirect pressure dispense connector including a pressurizing gas inlet that generally permits a gas pressure in-line to be inserted through or coupled with the dispense connector and be in fluid communication with the annular space between the liner and an exterior overpack. In such a system, a pressurizing fluid, gas, or other suitable substance may be introduced into the annular space, causing the liner to collapse away from the overpack wall, thereby pushing the contents of the liner out through a liquid outlet of the indirect pressure dispense connector.
In such pressure dispense applications, gas may permeate or be otherwise undesirably introduced through the liner material, thereby contaminating the retained liquids over time, as the gas will be permitted to go into the solution and undesirably come out into the manufacturing process, e.g., onto a semiconductor wafer as bubbles. Additionally, depending on the contents stored in a liner-based system, the liner may need to be manufactured from a material with high chemical resistance. For example, perfluoroalkoxy (PFA) is a fluoropolymer known to have great chemical resistance to hazardous materials, such as to photoresists. However, use of PFA for a liner material is limited where gas barrier properties are required, such as in indirect pressure dispense applications, described above. Polychlorotrifluoroethylene (PCTFE) is a fluoropolymer known to have reasonably good gas barrier properties. However, PCTFE has relatively poor chemical resistance and poor weldability to itself. Other conventional liners made using polyethelene or nylons similarly provide reasonably good gas barrier properties, but have relatively poor chemical resistance.
Thus, there is a need in the art for polymer-based multilayer gas barrier films, particularly fluoropolymer-based multilayer films with relatively good chemical resistance and relatively high gas barrier properties. More particularly, there is a need for polymer-based or fluoropolymer-based multilayer films with high gas barrier properties for use in manufacturing, for example but not limited to, liners for liner-based storage and dispensing systems. Often the contents of such liners include materials that can be very expensive, for example upwards of about $2,500/L or more. Thus, even a small increase in chemical resistance and/or the ability to decrease the amount of gas permeating into the liner during indirect pressure dispense applications, can be desirable.